High Mobility 4H-SiC MOSFET Using a Thin SiO2/Al2O3 Gate Stack

Enhancement mode 4H-SiC MOSFETs with a channel length of 2 μm achieved a room temperature field effect mobility of 125 cm
²
/V·s and a subthreshold slope of 130 mV/dec. The devices demonstrated a remarkable temperature stability up to 300 °C, remaining enhancement mode with high mobility and an ON/OFF current ratio in excess of 10
⁶
. The fabricated devices utilised a gate stack comprising a 0.7 nm thin thermal SiO
₂
, thereby reducing defects following oxidation, and a 40 nm thick Al
₂
O
₃
formed by atomic layer deposition. A high mobility was maintained over a wide gate voltage range.